Fast Models Reference Manual - ARM Information Center

Signaling and Clocking Protocols
Verification and testing
Validation of the ClockTimer component consisted of booting operating systems and VE test
suites on a VE model that contained a ClockTimer component.
Performance
An active ClockTimer component incurs no simulation overhead. For best performance, avoid
having your performance-critical code frequently cancel timers or query the number of
remaining ticks.
Library dependencies
The ClockTimer component has no dependencies on external libraries.
3.3.4 ClockTimer64 component
The ClockTimer component provides a mechanism for other components to schedule a callback
after a number of ticks at a given ClockSignal rate.
Figure 3-3 on page 3-6 shows a view of the component in System Canvas.
This component is written in C++.
Figure 3-4 ClockTimer64 in System Canvas
Ports
Table 3-4 on page 3-7 provides a brief description of the ClockTimer component ports.
Name Port protocol Type Description
Table 3-5 ClockTimer ports
timer_callback TimerCallback64 master port on which a signal is sent after the
number of scheduled ticks has elapsed
timer_control TimerControl64 slave allows the timer to be set, canceled and
queried
clk_in ClockSignal slave determines the tick rate of the timer
TimerControl64 protocol
The TimerControl protocol is used to control the actions of a ClockTimer component. It allows
a timer to be set to schedule a callback after a given number of ticks at the rate of the clock input.
If a timer is set while it is counting starts counting the new number of ticks without sending the
original callback. Cancelling a timer when it is not active has no effect.
The TimerControl protocol has the following behaviors:
set(uint64_t ticks) : void
sets the timer to countdown the given number of ticks
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